1. Field of the Invention
The present invention relates generally to acoustic sensors, and more particularly, to an implantable acoustic sensor.
2. Related Art
Hearing loss, which may be due to many different causes, is generally of two types, conductive and sensorineural. In some cases, a person suffers from hearing loss of both types. Conductive hearing loss occurs when the normal mechanical pathways for sound to reach the cochlea are impeded, for example, by damage to the ossicles. Individuals who suffer from conductive hearing loss typically have some form of residual hearing because the hair cells in the cochlea are undamaged. As a result, individuals suffering from conductive hearing loss typically receive an implantable hearing prosthesis that generates mechanical motion of the cochlea fluid. Some such hearing prostheses, such as acoustic hearing aids, middle ear implants, etc., include one or more components implanted in the recipient, and are referred to herein as implantable hearing prostheses.
In many people who are profoundly deaf, however, the reason for their deafness is sensorineural hearing loss. Sensorineural hearing loss occurs when there is damage to the inner ear, or to the nerve pathways from the inner ear to the brain. As such, many individuals suffering from sensorineural hearing loss are thus unable to derive suitable benefit from hearing prostheses that generate mechanical motion of the cochlea fluid. As a result, implantable hearing prostheses that deliver electrical stimulation to nerve cells of the recipient's auditory system have been developed for persons whom do not derive adequate benefit from conventional hearing aids. Such electrically-stimulating hearing prostheses deliver electrical stimulation to nerve cells of the recipient's auditory system thereby providing the recipient with a hearing percept. Electrically-stimulating hearing prostheses include, for example, auditory brain stimulators and cochlear prostheses (commonly referred to as cochlear prosthetic devices, cochlear implants, cochlear devices, and the like; simply “cochlear implants” herein.)
Oftentimes sensorineural hearing loss is due to the absence or destruction of the cochlear hair cells which transduce acoustic signals into nerve impulses. It is for this purpose that cochlear implants have been developed. Cochlear implants provide a recipient with a hearing percept by delivering electrical stimulation signals directly to the auditory nerve cells, thereby bypassing absent or defective hair cells that normally transduce acoustic vibrations into neural activity. Such devices generally use an electrode array implanted in the cochlea so that the electrodes may differentially activate auditory neurons that normally encode differential pitches of sound.
Auditory brain stimulators are used to treat a smaller number of recipients with bilateral degeneration of the auditory nerve. For such recipients, the auditory brain stimulator provides stimulation of the cochlear nucleus in the brainstem.
Totally or fully implantable forms of the above and other implantable hearing prostheses have been developed to treat a recipient's conductive, sensorineural and/or combination hearing loss. As used herein, a totally implantable hearing prosthesis refers to an implantable prosthesis that is capable of operating, at least for a finite period of time, without an external device.